Process reactor systems are used in semiconductor technology to etch or deposit materials on semiconductor wafers. For example, a metal-organic chemical vapor deposition (MOCVD) reactor can be used to deposit high-dielectric-constant (high-K) dielectric films in the area of semiconductor nanochips technology, or to grow a crystal in the area of optoelectronics technology such as lasers and light emitting diodes (LED). Some of these processes build on the concept of atomic layer deposition (ALD) and employ gases made of small molecules.
In a typical process using a precursor material such as a gas or liquid of metal-organic compound, for example the MOCVD reactor, the precursor material is stored in a bubbler and delivered into a chamber of the reactor. The compound in the bubbler is usually required to have a specific temperature, defined by the process, for controlled delivery into the reactor. The required temperature of a specific compound in a bubbler may vary in the range of −20° C. to +70° C. In many conventional process reactor systems, the bubbler is placed and often submerged in a liquid of an open bath for temperature control. The bubbler and the bath may sit in an electronics or utilities enclosure, where other components and electronics of the reactor system are disposed. An open bath can lead to problems when the temperature of such liquid is above its evaporation temperature, for example room temperature, in which case the evaporation of the liquid can cause shortage or corrosion in the electronics or other instrumentation of the reactor system, particularly those inside the utility enclosure. If the temperature of the liquid in the bath is below its condensation temperature, for example room temperature, the resulting condensation may change the ratio of glycol in the reactor system. If the temperature of the liquid drops below 0° C., nearby components of the reactor system may freeze and stop operation.
Conventional apparatus for controlling the temperature of bubblers can typically take two to four hours to start up, resulting in reduced total available uptime or process time for the reactor system. Even when such apparatus are up and running, many of the currently available process reactor systems do not effectively control the temperature of the gas or compound delivered by the bubbler. Without accurate temperature control, the processes performed by the process reactor systems may be undesirably affected. For example, the temperature instability of the bath holding the bubbler can result in instability in electronics calibration and performance drift.
In certain exemplary applications, the precursor material can be a metal-organic liquid used to grow a crystal by atomic layer deposition to form part of an LED structure. Since the precursor material is used to grow a crystal inside of the reactor, it may need to be in a certain proportion with other materials when it is delivered into the chamber of the reactor. This cannot be achieved easily without precise temperature control of the bubbler because unwanted temperature changes in the metal-organic compounds often cause unwanted dose deviation during the deposition process.